Package it.unimi.dsi.fastutil.ints

Class IntArrayList

java.lang.Object

java.util.AbstractCollection<Integer>

it.unimi.dsi.fastutil.ints.AbstractIntCollection

it.unimi.dsi.fastutil.ints.AbstractIntList

it.unimi.dsi.fastutil.ints.IntArrayList

All Implemented Interfaces:

IntCollection, IntIterable, IntList, IntStack, Stack<Integer>, Serializable, Cloneable, Comparable<List<? extends Integer>>, Iterable<Integer>, Collection<Integer>, List<Integer>, RandomAccess

public class IntArrayList
extends AbstractIntList
implements RandomAccess, Cloneable, Serializable

A type-specific array-based list; provides some additional methods that use polymorphism to avoid (un)boxing.

This class implements a lightweight, fast, open, optimized, reuse-oriented version of array-based lists. Instances of this class represent a list with an array that is enlarged as needed when new entries are created (by doubling its current length), but is never made smaller (even on a clear()). A family of trimming methods lets you control the size of the backing array; this is particularly useful if you reuse instances of this class. Range checks are equivalent to those of java.util's classes, but they are delayed as much as possible. The backing array is exposed by the elements() method.

This class implements the bulk methods removeElements(), addElements() and getElements() using high-performance system calls (e.g., System.arraycopy() instead of expensive loops.

See Also:

ArrayList, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class it.unimi.dsi.fastutil.ints.AbstractIntList

AbstractIntList.IntSubList

Field Summary

Fields

Modifier and Type	Field	Description
static int	DEFAULT_INITIAL_CAPACITY	The initial default capacity of an array list.

Constructor Summary

Constructors

Constructor	Description
IntArrayList()	Creates a new array list with DEFAULT_INITIAL_CAPACITY capacity.
IntArrayList(int capacity)	Creates a new array list with given capacity.
IntArrayList(int[] a)	Creates a new array list and fills it with the elements of a given array.
IntArrayList(int[] a, int offset, int length)	Creates a new array list and fills it with the elements of a given array.
IntArrayList(IntCollection c)	Creates a new array list and fills it with a given type-specific collection.
IntArrayList(IntIterator i)	Creates a new array list and fills it with the elements returned by a type-specific iterator..
IntArrayList(IntList l)	Creates a new array list and fills it with a given type-specific list.
IntArrayList(Collection<? extends Integer> c)	Creates a new array list and fills it with a given collection.
IntArrayList(Iterator<? extends Integer> i)	Creates a new array list and fills it with the elements returned by an iterator..

Method Summary

Modifier and Type	Method	Description
boolean	add(int k)	Ensures that this collection contains the specified element (optional operation).
void	add(int index, int k)	Inserts the specified element at the specified position in this list (optional operation).
boolean	addAll(int index, IntCollection c)	Inserts all of the elements in the specified type-specific collection into this type-specific list at the specified position (optional operation).
boolean	addAll(int index, IntList l)	Inserts all of the elements in the specified type-specific list into this type-specific list at the specified position (optional operation).
void	addElements(int index, int[] a, int offset, int length)	Adds elements to this type-specific list using optimized system calls.
void	clear()
IntArrayList	clone()
int	compareTo(IntArrayList l)	Compares this array list to another array list.
int[]	elements()	Returns the backing array of this list.
void	ensureCapacity(int capacity)	Ensures that this array list can contain the given number of entries without resizing.
boolean	equals(IntArrayList l)	Compares this type-specific array list to another one.
void	getElements(int from, int[] a, int offset, int length)	Copies element of this type-specific list into the given array using optimized system calls.
int	getInt(int index)	Returns the element at the specified position in this list.
int	indexOf(int k)	Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
boolean	isEmpty()	Checks whether the stack is empty.
int	lastIndexOf(int k)	Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.
IntListIterator	listIterator(int index)	Returns a type-specific list iterator on the list starting at a given index.
boolean	rem(int k)	Removes a single instance of the specified element from this collection, if it is present (optional operation).
boolean	removeAll(IntCollection c)	Remove from this collection all elements in the given type-specific collection.
boolean	removeAll(Collection<?> c)
void	removeElements(int from, int to)	Removes elements of this type-specific list using optimized system calls.
int	removeInt(int index)	Removes the element at the specified position in this list (optional operation).
int	set(int index, int k)	Replaces the element at the specified position in this list with the specified element (optional operation).
int	size()
void	size(int size)	Sets the size of this list.
int[]	toArray(int[] a)	Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.
void	trim()	Trims this array list so that the capacity is equal to the size.
void	trim(int n)	Trims the backing array if it is too large.
static IntArrayList	wrap(int[] a)	Wraps a given array into an array list.
static IntArrayList	wrap(int[] a, int length)	Wraps a given array into an array list of given size.

Methods inherited from class it.unimi.dsi.fastutil.ints.AbstractIntList

addAll, addAll, addAll, addAll, addElements, compareTo, contains, equals, hashCode, iterator, listIterator, peekInt, popInt, push, subList, topInt, toString

Methods inherited from class it.unimi.dsi.fastutil.ints.AbstractIntCollection

add, contains, containsAll, remove, retainAll, toIntArray, toIntArray

Methods inherited from class java.util.AbstractCollection

containsAll, retainAll, toArray, toArray

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Collection

parallelStream, stream, toArray

Methods inherited from interface it.unimi.dsi.fastutil.ints.IntCollection

containsAll, removeIf, removeIf, retainAll, toIntArray, toIntArray

Methods inherited from interface it.unimi.dsi.fastutil.ints.IntIterable

forEach, forEach

Methods inherited from interface it.unimi.dsi.fastutil.ints.IntList

add, add, contains, get, indexOf, lastIndexOf, remove, remove, set

Methods inherited from interface it.unimi.dsi.fastutil.ints.IntStack

peek, pop, push, top

Methods inherited from interface java.util.List

containsAll, replaceAll, retainAll, sort, spliterator, toArray, toArray

Field Detail

DEFAULT_INITIAL_CAPACITY

public static final int DEFAULT_INITIAL_CAPACITY

The initial default capacity of an array list.

See Also:

Constant Field Values

Constructor Detail

IntArrayList

public IntArrayList(int capacity)

Creates a new array list with given capacity.

Parameters:

capacity - the initial capacity of the array list (may be 0).

IntArrayList

public IntArrayList()

Creates a new array list with DEFAULT_INITIAL_CAPACITY capacity.

IntArrayList

public IntArrayList(Collection<? extends Integer> c)

Creates a new array list and fills it with a given collection.

Parameters:

c - a collection that will be used to fill the array list.

IntArrayList

public IntArrayList(IntCollection c)

Creates a new array list and fills it with a given type-specific collection.

Parameters:

c - a type-specific collection that will be used to fill the array list.

IntArrayList

public IntArrayList(IntList l)

Creates a new array list and fills it with a given type-specific list.

Parameters:

l - a type-specific list that will be used to fill the array list.

IntArrayList

public IntArrayList(int[] a)

Creates a new array list and fills it with the elements of a given array.

Parameters:

a - an array whose elements will be used to fill the array list.

IntArrayList

public IntArrayList(int[] a,
                    int offset,
                    int length)

Creates a new array list and fills it with the elements of a given array.

Parameters:

a - an array whose elements will be used to fill the array list.

offset - the first element to use.

length - the number of elements to use.

IntArrayList

public IntArrayList(Iterator<? extends Integer> i)

Creates a new array list and fills it with the elements returned by an iterator..

Parameters:

i - an iterator whose returned elements will fill the array list.

IntArrayList

public IntArrayList(IntIterator i)

Creates a new array list and fills it with the elements returned by a type-specific iterator..

Parameters:

i - a type-specific iterator whose returned elements will fill the array list.

Method Detail

elements

public int[] elements()

Returns the backing array of this list.

Returns:

the backing array.

wrap

public static IntArrayList wrap(int[] a,
                                int length)

Wraps a given array into an array list of given size.

Note it is guaranteed that the type of the array returned by elements() will be the same (see the comments in the class documentation).

Parameters:

a - an array to wrap.

length - the length of the resulting array list.

Returns:

a new array list of the given size, wrapping the given array.

wrap

public static IntArrayList wrap(int[] a)

Wraps a given array into an array list.

Note it is guaranteed that the type of the array returned by elements() will be the same (see the comments in the class documentation).

Parameters:

a - an array to wrap.

Returns:

a new array list wrapping the given array.

ensureCapacity

public void ensureCapacity(int capacity)

Ensures that this array list can contain the given number of entries without resizing.

Parameters:

capacity - the new minimum capacity for this array list.

add

public void add(int index,
                int k)

Description copied from class: AbstractIntList

Inserts the specified element at the specified position in this list (optional operation).

This implementation always throws an UnsupportedOperationException.

Specified by:

add in interface IntList

Overrides:

add in class AbstractIntList

See Also:

List.add(int,Object)

add

public boolean add(int k)

Description copied from class: AbstractIntList

Ensures that this collection contains the specified element (optional operation).

This implementation always throws an UnsupportedOperationException.

This implementation delegates to the type-specific version of List.add(int, Object).

Specified by:

add in interface IntCollection

Specified by:

add in interface IntList

Overrides:

add in class AbstractIntList

See Also:

Collection.add(Object)

getInt

public int getInt(int index)

Description copied from interface: IntList

Returns the element at the specified position in this list.

Specified by:

getInt in interface IntList

See Also:

List.get(int)

indexOf

public int indexOf(int k)

Description copied from interface: IntList

Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.

Specified by:

indexOf in interface IntList

Overrides:

indexOf in class AbstractIntList

See Also:

List.indexOf(Object)

lastIndexOf

public int lastIndexOf(int k)

Description copied from interface: IntList

Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.

Specified by:

lastIndexOf in interface IntList

Overrides:

lastIndexOf in class AbstractIntList

See Also:

List.lastIndexOf(Object)

removeInt

public int removeInt(int index)

Description copied from class: AbstractIntList

Removes the element at the specified position in this list (optional operation).

This implementation always throws an UnsupportedOperationException.

Specified by:

removeInt in interface IntList

Overrides:

removeInt in class AbstractIntList

See Also:

List.remove(int)

rem

public boolean rem(int k)

Description copied from class: AbstractIntList

Removes a single instance of the specified element from this collection, if it is present (optional operation).

This implementation delegates to indexOf().

Specified by:

rem in interface IntCollection

Overrides:

rem in class AbstractIntList

See Also:

List.remove(Object)

set

public int set(int index,
               int k)

Description copied from class: AbstractIntList

Replaces the element at the specified position in this list with the specified element (optional operation).

This implementation always throws an UnsupportedOperationException.

Specified by:

set in interface IntList

Overrides:

set in class AbstractIntList

See Also:

List.set(int,Object)

clear

public void clear()

Description copied from class: AbstractIntList

This implementation delegates to AbstractIntList.removeElements(int, int).

Specified by:

clear in interface Collection<Integer>

Specified by:

clear in interface List<Integer>

Overrides:

clear in class AbstractIntList

size

public int size()

Specified by:

size in interface Collection<Integer>

Specified by:

size in interface List<Integer>

Specified by:

size in class AbstractCollection<Integer>

size

public void size(int size)

Description copied from interface: IntList

Sets the size of this list.

If the specified size is smaller than the current size, the last elements are discarded. Otherwise, they are filled with 0/null/false.

Specified by:

size in interface IntList

Overrides:

size in class AbstractIntList

Parameters:

size - the new size.

isEmpty

public boolean isEmpty()

Description copied from interface: Stack

Checks whether the stack is empty.

Specified by:

isEmpty in interface Collection<Integer>

Specified by:

isEmpty in interface List<Integer>

Specified by:

isEmpty in interface Stack<Integer>

Overrides:

isEmpty in class AbstractCollection<Integer>

Returns:

true if the stack is empty.

trim

public void trim()

Trims this array list so that the capacity is equal to the size.

See Also:

ArrayList.trimToSize()

trim

public void trim(int n)

Trims the backing array if it is too large. If the current array length is smaller than or equal to n, this method does nothing. Otherwise, it trims the array length to the maximum between n and size().

This method is useful when reusing lists. Clearing a list leaves the array length untouched. If you are reusing a list many times, you can call this method with a typical size to avoid keeping around a very large array just because of a few large transient lists.

Parameters:

n - the threshold for the trimming.

getElements

public void getElements(int from,
                        int[] a,
                        int offset,
                        int length)

Copies element of this type-specific list into the given array using optimized system calls.

Specified by:

getElements in interface IntList

Overrides:

getElements in class AbstractIntList

Parameters:

from - the start index (inclusive).

a - the destination array.

offset - the offset into the destination array where to store the first element copied.

length - the number of elements to be copied.

removeElements

public void removeElements(int from,
                           int to)

Removes elements of this type-specific list using optimized system calls.

Specified by:

removeElements in interface IntList

Overrides:

removeElements in class AbstractIntList

Parameters:

from - the start index (inclusive).

to - the end index (exclusive).

addElements

public void addElements(int index,
                        int[] a,
                        int offset,
                        int length)

Adds elements to this type-specific list using optimized system calls.

Specified by:

addElements in interface IntList

Overrides:

addElements in class AbstractIntList

Parameters:

index - the index at which to add elements.

a - the array containing the elements.

offset - the offset of the first element to add.

length - the number of elements to add.

toArray

public int[] toArray(int[] a)

Description copied from interface: IntCollection

Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.

Note that, contrarily to Collection.toArray(Object[]), this methods just writes all elements of this collection: no special value will be added after the last one.

Specified by:

toArray in interface IntCollection

Overrides:

toArray in class AbstractIntCollection

Parameters:

a - if this array is big enough, it will be used to store this collection.

Returns:

a primitive type array containing the items of this collection.

See Also:

Collection.toArray(Object[])

addAll

public boolean addAll(int index,
                      IntCollection c)

Description copied from interface: IntList

Inserts all of the elements in the specified type-specific collection into this type-specific list at the specified position (optional operation).

Specified by:

addAll in interface IntList

Overrides:

addAll in class AbstractIntList

See Also:

List.addAll(int,java.util.Collection)

addAll

public boolean addAll(int index,
                      IntList l)

Description copied from class: AbstractIntList

Inserts all of the elements in the specified type-specific list into this type-specific list at the specified position (optional operation).

This implementation delegates to the type-specific version of List.addAll(int, Collection).

Specified by:

addAll in interface IntList

Overrides:

addAll in class AbstractIntList

See Also:

List.add(int,Object)

removeAll

public boolean removeAll(IntCollection c)

Description copied from interface: IntCollection

Remove from this collection all elements in the given type-specific collection.

Specified by:

removeAll in interface IntCollection

Overrides:

removeAll in class AbstractIntCollection

Parameters:

c - a type-specific collection.

Returns:

true if this collection changed as a result of the call.

See Also:

Collection.removeAll(Collection)

removeAll

public boolean removeAll(Collection<?> c)

Specified by:

removeAll in interface Collection<Integer>

Specified by:

removeAll in interface List<Integer>

Overrides:

removeAll in class AbstractCollection<Integer>

listIterator

public IntListIterator listIterator(int index)

Description copied from class: AbstractIntList

Returns a type-specific list iterator on the list starting at a given index.

This implementation is based on the random-access methods.

Specified by:

listIterator in interface IntList

Specified by:

listIterator in interface List<Integer>

Overrides:

listIterator in class AbstractIntList

See Also:

List.listIterator(int)

clone

public IntArrayList clone()

equals

public boolean equals(IntArrayList l)

Compares this type-specific array list to another one.

This method exists only for sake of efficiency. The implementation inherited from the abstract implementation would already work.

Parameters:

l - a type-specific array list.

Returns:

true if the argument contains the same elements of this type-specific array list.

compareTo

public int compareTo(IntArrayList l)

Compares this array list to another array list.

This method exists only for sake of efficiency. The implementation inherited from the abstract implementation would already work.

Parameters:

l - an array list.

Returns:

a negative integer, zero, or a positive integer as this list is lexicographically less than, equal to, or greater than the argument.